The study was carried out by researchers from University of Otago Medical School, New Zealand. Funding was provided by Genesis Oncology Trust, the Dean’s Bequest Funds of the Dunedin School of Medicine, the Gisborne East Coast Cancer Research Trust and the Director’s Cancer Research Trust. The research was published in the peer-reviewed American Journal of Epidemiology. This was a case-control study in New Zealand that compared a group of adults with bowel cancer, and a group without bowel cancer, and looked at whether they drank milk at school. School milk was freely available in most schools in New Zealand until 1967 when the government programme was stopped. Many schools in the Southland region stopped free milk as long ago as 1950.
Case-control studies are appropriate for looking at whether people with and without a disease have had a particular exposure (milk in this case). The difficulty is in accounting for all potential confounding factors, particularly other health and lifestyle factors, which could be related to both diet and bowel cancer risk, for example regular childhood milk consumption could be a reflection of a ‘healthy’ diet and other healthy lifestyle behaviours that may reduce risk of cancer. In addition, when examining such a specific dietary factor – ie milk consumed in school – it is difficult to account for all possible milk or other dairy products consumed outside of school.
In this case-control study, 562 adults (aged 30 to 69) with newly diagnosed bowel cancer were identified from the New Zealand Cancer Registry in 2007. For a control group, 571 age-matched adults without cancer were randomly selected from the electoral register. All participants were mailed a questionnaire that asked about any previous illness, use of aspirin or dietary supplements in childhood, participation in school milk programmes, other childhood milk consumption, childhood diet (including other milk and dairy), smoking, alcohol consumption prior to 25 years of age, screening tests for bowel cancer, family history of cancer, education and sociodemographic characteristics. Childhood weight and height were not questioned. For school milk consumption they were specifically asked:
- Whether they drank school milk
- How many half-pint bottles they drank a week
- What age they first drank school milk
- When they stopped drinking school milk
Statistical risk associations between school milk participation and cancer were calculated. The calculations took into account several risk factors for bowel cancer risk including age, sex, ethnicity and family history.
What were the basic results?
Data on school milk consumption was available for 552 cases and 569 controls. As expected, people who started school before 1967 were more likely to have had free school milk than those who began school after 1968. Seventy-eight percent of cases participated in the school milk programme compared with 82% of controls. School milk consumption was associated with a 30% reduced risk of developing bowel cancer (odds ratio 0.70, 95% confidence interval 0.51 to 0.96).
When looking at the effect of number of bottles consumed per week they found that compared with no bottles, five bottles per week was associated with 32% significantly decreased risk, and 10 or more bottles with 61% significantly decreased risk. However, there was no significant association with one to four bottles or six to nine bottles. The researchers found a similar trend when the total school consumption of milk was compared with no consumption: 1,200-1,599 bottles was associated with 38% significantly decreased risk; 1,600-1,799 with 43% decreased risk; and 1,800 or more bottles associated with 38% significantly decreased risk. There was no significant association with fewer than 1,200 bottles. The researchers calculated that for every 100 half-pint bottles consumed at school there was a 2.1% reduction in the risk of bowel cancer. Outside of school, there was a significantly reduced risk of bowel cancer with more than 20 dairy products a week compared with none to nine dairy products a week.
The researchers conclude that their national case-control study ‘provides evidence that school milk consumption was associated with a reduction in the risk of adult colorectal cancer in New Zealand. Furthermore, a dose-dependent relation was evident’. This study has strengths in its relatively large size, its reliable and nationally representative identification of cases and controls, and its thorough data collection. However, the conclusion that school milk consumption is associated with a reduced risk of bowel cancer in adulthood must be interpreted in light of a number of considerations:
The analysis took into account established risk factors for bowel cancer including age, sex, ethnicity and family history. However, many other potential confounders were not considered, including diet, physical activity, overweight and obesity, smoking or alcohol consumption. Diet in particular has been implicated in bowel cancer risk, with diets high in saturated fat, red meat and processed foods and low in fibre, fruit and vegetables thought to increase risk. Potentially, any of these lifestyle behaviours could be confounding the relationship between school milk consumption and bowel cancer and regular childhood milk consumption could be a reflection of a ‘healthy’ diet and other healthy lifestyle behaviours that reduce risk of cancer. When looking at the effect of number of bottles consumed per week, the researchers found that, compared with no bottles, five bottles were associated with 32% significantly decreased risk and 10 or more bottles with 61% significantly decreased risk. However, there was no significant association with one to four bottles or six to nine bottles. Therefore, the trend here is not very clear. Particularly as only 16 cases and 31 controls drank 10 or more bottles a week, statistical comparison between such small numbers should be viewed with caution. With many food questionnaires there is the potential for recall bias. For example, adults may have difficulty remembering how many bottles of school milk they drank many years before. When estimating their average weekly amount, it is highly possible that this could be inaccurate or that their consumption varied slightly from week to week and year to year. Particularly when researchers were using this response and combining it with the number of weeks in the school year and their total years at school to give a total number of bottles consumed at school (figures in 100s or 1,000s), there is the possibility of being incorrectly categorised. Hence, there may be less reliability when calculating risk according to the category of total milk bottles consumed. Cancer prevalence, and particularly environmental and lifestyle risk factors for cancer, can vary between countries. These findings in New Zealand may not be represented elsewhere. Of note, the researchers acknowledge that a cohort study in the UK found the opposite: increased childhood dairy consumption was associated with increased risk of bowel cancer. Case-control studies are most appropriate for looking at rare diseases, where you would expect there to be only a small number of cases developing among a large number of people. In the case of bowel cancer, which is common, the slightly more reliable cohort design could have also been used, where children who drank milk at school and those who didn’t were followed over time to see if they developed cancer. However, such a cohort would consequently need extensive long-term follow-up.
The possible association between milk/dairy consumption, or calcium intake, in childhood, or in later years, is worthy of further study. However, from this study alone, it cannot be concluded that school milk prevents bowel cancer later in life.
New findings from the Monell Center reveal that weight gain of formula-fed infants is influenced by the type of formula the infant is consuming. The findings have implications related to the infant’s risk for the development of obesity, diabetes and other diseases later in life. “Events early in life have long-term consequences on health and one of the most significant influences is early growth rate,” said study lead author Julie Mennella, Ph.D., a developmental psychobiologist at Monell. “We already know that formula-fed babies gain more weight than breast-fed babies. But we didn’t know whether this was true for all types of formula.”
While most infant formulas are cow’s milk-based, other choices include soy-based and protein hydrolysate-based formulas. Protein hydrolysate formulas contain pre-digested proteins and typically are fed to infants who cannot tolerate the intact proteins in other formulas. In adults, pre-digested proteins are believed to act in the intestine to initiate the end of a meal, thus leading to smaller meals and intake of fewer calories. Based on this, the authors hypothesized that infants who were feeding protein hydrolysate formulas would eat less and have an altered growth pattern relative to infants feeding cow’s milk-based formula.
In the study, published online in the journal Pediatrics, infants whose parents had already decided to bottle-feed were randomly assigned at two weeks of age to feed either a cow’s milk-based formula (35 infants) or a protein hydrolysate formula (24 infants) for seven months. Both formulas contained the same amount of calories, but the hydrolysate formula had more protein, including greater amounts of small peptides and free amino acids. Infants were weighed once each month in the laboratory, where they also were videotaped consuming a meal of the assigned formula. The meal continued until the infant signaled that s/he was full.
Over the seven months of the study, the protein hydrolysate infants gained weight at a slower rate than infants fed cow milk formula. Linear growth, or length, did not differ between the two groups, demonstrating that the differences in growth were specifically attributable to weight. “All formulas are not alike,” said Mennella. “These two formulas have the same amount of calories, but differ considerably in terms of how they influence infant growth.”
When the data were compared to national norms for breast-fed infants, the rate of weight gain of protein hydrolysate infants was comparable to the breast milk standards; in contrast, infants fed cow’s milk formula gained weight at a greater rate than the same breast milk standards. Analysis of the laboratory meal revealed the infants fed the protein hydrolysate formula consumed less formula during the meal. “One of the reasons the protein hydrolysate infants had similar growth patterns to breast-fed infants, who are the gold standard, is that they consumed less formula during a feed as compared to infants fed cow’s milk formula” said Mennella. “The next question to ask is: Why do infants on cow’s milk formula overfeed?”
The findings highlight the need to understand the long-term influences of infant formula composition on feeding behavior, growth, and metabolic health. Future studies will utilize measures of energy metabolism and expenditure to examine how the individual formulas influence growth, and how each differs from breastfeeding. Also contributing to the study, which was funded by the National Institute of Child Health and Human Development, were Monell scientists Gary Beauchamp and Alison Ventura.
Individuals who drink three glasses of milk a day decrease their risk of cardiovascular disease by 18 percent, according to new research published in the American Journal of Clinical Nutrition.Researchers at Wageningen University and Harvard University examined 17 studies from the United States, Europe and Japan and found no link between the consumption of regular or low fat dairy and any increased risk of heart disease, stroke or total mortality. “Milk and dairy are the most nutritious and healthy foods available and loaded with naturally occurring nutrients, such as calcium, potassium and protein, to name a few,” said Cindy Schweitzer, technical director of the Global Dairy Platform. “It's about going back to the basics; maintaining a healthy lifestyle doesn't have to be a scientific equation.”
Schweitzer said during the past three decades as research sought to understand influencers of cardiovascular disease, simplified dietary advice including consuming only low fat dairy products emerged. However, in 2010 alone, a significant amount of new research was published from all over the world, supporting the health benefits of dairy. From dispelling the myth that dairy causes heart disease, to revealing dairy's weight loss-benefits, the following is a roundup of select dairy research conducted in 2010:
- U.S. researchers examined 21 studies that included data from nearly 350,000 and concluded that dietary intakes of saturated fats are not associated with increases in the risk of either coronary heart disease or cardiovascular disease. The study was published in the American Journal of Clinical Nutrition.
- A study published in the American Journal of Epidemiology examined 23,366 Swedish men and revealed that intakes of calcium above the recommended daily levels may reduce the risk of mortality from heart disease and cancer by 25 percent.
- An Australian study published in the European Journal of Clinical Nutrition concluded that overall intake of dairy products was not associated with mortality. The 16-year prospective study of 1,529 Australian adults found that people who ate the most full-fat dairy had a 69-percent lower risk of cardiovascular death than those who ate the least.
- A Danish study published in Physiology & Behavior concluded that an inadequate calcium intake during an energy restricted weight-loss program may trigger hunger and impair compliance to the diet.
- An Israeli study published in the American Journal of Clinical Nutrition showed that a higher dairy calcium intake is related to greater diet-induced weight loss. The study sampled more than 300 overweight men and women during two years and found those with the highest dairy calcium intake lost 38-percent more weight than those with the lowest dairy calcium intake.
The amount of dairy recommended per day varies by country and is generally based on nutrition needs and food availability. “In the US and some European countries, three servings of dairy foods are recommended daily, said Dr. Schweitzer.”
The scientists looked for three nucleotides in breast milk (adenosine, guanosine and uridine), which excite or relax the central nervous system, promoting restfulness and sleep, and observed how these varied throughout a 24-hour period.
“You wouldn't give anyone a coffee at night, and the same is true of milk – it has day-specific ingredients that stimulate activity in the infant, and other night-time components that help the baby to rest”, explains Sánchez.
The benefits of breast milk
The World Health Organisation (WHO) says breast milk is the best food for the newborn, and should not be substituted, since it meets all the child's physiological requirements during the first six months of life. It not only protects the baby against many illnesses such as colds, diarrhoea and sudden infant death syndrome, but can also prevent future diseases such as asthma, allergies and obesity, and promotes intellectual development.
The benefits of breastfeeding also extend to the mother. Women who breastfeed lose the weight gained during pregnancy more quickly, and it also helps prevent against anaemia, high blood pressure and postnatal depression. Osteoporosis and breast cancer are also less common among women who breastfeed their children.
There are some tricks that can help make any fast food meal better for you and your family. Follow these tips to cut down on fat, sodium, sugar, overall calories and make your meal healthier:
- If you are ordering á la Carte items on the menu, find out if there is a child’s size available. Another option is to order the regular size and split the order and share it. Avoid ordering extra large portions just because they are a deal! These deals usually have the words jumbo, giant, super sized or deluxe in the name.
- Don’t be shy about making substitutions! Children love kid’s meals because it comes with a toy and it is usually in a cool looking box. Let them order it but ask to make substitutions for the fries and soda if possible. Many restaurants will offer milk or water as a beverage and apple slices instead of fries.
- Talk to your child before ordering a meal and give them a choice of milk, juice or water (make sure it is low fat milk or 100% fruit juice.) Explain to them that soda is high in empty calories that will just fill up their tummies.
- Let your child know that they can ask for items prepared a specific way. For example, salad dressing on the side, baked or grilled instead of fried, brown rice instead of white rice.
- Finally, set a good example by ordering a healthy meal for yourself.
What Can Parents Do?
By learning how the food is prepared, you will be able to make healthier choices ordering from a menu:
- Order foods that are not breaded or fried because they are higher in fat and calories. Foods that are breaded and deep fried include: chicken nuggets, fried chicken, fried fish sandwiches, onion rings and french fries.
- Order foods that are prepared by being steamed, broiled, grilled, poached, or roasted.
- Have gravy, sauces and dressings served on the side so you can control the amount you eat.
- Use salsa and mustard instead of mayonnaise.
- Use non-fat milk or low fat milk instead of whole milk or heavy cream.
- Order a salad with ‘lite’ or non-fat dressing instead of regular dressing.
- Choose a regular, single patty hamburger without mayonnaise and cheese.
Over the last few years, many chain restaurants have been adding healthier menu options. They also started providing nutrition information for all the foods on the menu, but you usually need to ask for it. Try checking their website as well for additional information.
Hamburger fast food restaurants are the most popular with children. However, other options are available such as Asian food, sandwiches, or Mexican grills. Keep in mind that every fast food restaurant has both healthy and less-healthy choices. Here are some pointers to remember that can help you make better choices when eating out at various fast food places:
- Choose grilled soft tacos or burritos instead of a crispy shell or gordita-type burritos.
- Black beans are a better choice because they have less fat than refried beans.
- Ahhh, the Mexican condiments! Salsa is low in calories and fat and it makes a great substitute for sour cream, guacamole and cheese.
- Choose lean meats such as chicken breast, lean ham or roast beef, instead of salami or bacon.
- Ask for 100% whole wheat bread for sandwiches. Skip the croissants and biscuits because they are high in fat.
- Add low fat salad dressings instead of special sauces or mayonnaise.
- Choose baked chips or pretzels instead of regular potato chips.
- Steamed brown rice has more nutrients and less calories than fried rice.
- Stir fried, steamed, roasted or broiled dishes are healthier choices than battered or deep fried.
- Sauces such as low sodium soy sauce, rice wine vinegar, wasabi, or ginger are better choices than sweet and sour sauce or coconut milk.
It’s OK to enjoy fast food once in a while, but try to limit the visits to no more than twice a month. An average meal at a fast food restaurant has around 1000 calories and does not have the vitamins, minerals and other important nutrients that your child needs to grow healthy and strong. While fast food consumption has greatly increased over the years there are several contributing factors why childhood obesity is becoming more and more prevalent. While all the above information is important, we need to keep things in perspective by understanding that the weight epidemic in this country is because of how much food children eat, rather than what food children eat.
If your family is going to have fast food for one meal, just make sure the other meals that day contain healthier foods like fruits and vegetables. Perhaps you could take an afternoon with your child and prepare a few homemade meals in advance that can be served quickly to avoid the temptation of getting fast food too often while at the same time teaching them some simple food preparation steps. Either way, just remember, it is not that difficult to eat healthy even when you don’t have much time.
This family wellness article is provided by Nourish Interactive, visitwww.nourishinteractive.com for nutrition articles, family wellness tips, free children's healthy games, and tools. Available in English and Spanish.
Copyright ©2009 Nourish Interactive – All Rights Reserved.
Let’s look at some examples:
You eat 2 waffles for breakfast
- One serving from the Food Guide Pyramid is equal to 1 waffle.
- So that means if you ate 2 waffles, you also ate 2 servings from the grains group.
Here are some other common portions and their respective Food Guide Pyramid serving sizes:
|Common portions that people eat
||Food Guide Pyramid Serving Size
||Total servings per Food Guide Pyramid
||= 2 servings
|1 English Muffin
||½ English muffin
||= 2 servings
|1 Hamburger bun
||= 2 servings
|1 cup cooked rice
||½ cup cooked rice
||= 2 servings
|1 cups cooked pasta
||½ cup cooked pasta
||= 2 servings
In each food group, look at these different Food Guide Pyramid examples indicating 1 serving each. How do these compare with what your portions look like?
- 1 slice bread, waffle or pancake
- ½ bagel, hamburger bun, or English muffin
- ½ cup cooked rice, pasta or cereal
- 1 cup ready to eat cereal
- ¾ cup (6 fluid ounces) 100% vegetable juice
- 1 cup raw, leafy vegetables or salad
- ½ cup cooked or canned vegetables
- 1 medium apple, orange or banana
- ½ cup fruit (canned, cooked or raw)
- ½ cup (4 fluid ounces) 100% fruit juice
- ¼ cup dried fruit (raisins, apricots or prunes)
- 1 cup milk or yogurt
- 2 ounces processed cheese (American)
- 1 ½ ounces natural cheese (cheddar)
- Meat and Beans
- 1 tablespoons of peanut butter counts as 1 ounce
- ¼ cup nuts or 20-24 almonds
- 1 medium size egg
- 2-3 ounces of poultry, meat or fish (2-3 servings)
- ¼ cup of beans
Tips on how to visually estimate 1 serving size
|1 oz. bread or 1 slice of bread
|10 French fries
||Deck of cards
|½ cup cooked rice or pasta
|1 cup raw leafy vegetables
|½ cup vegetables
|1 medium fruit such as an apple or an orange
||Tennis ball or the size of your fist
|¾ cup juice
||6 ounce juice can (1 ½ servings)
|½ cup chopped or canned fruit
|Milk and Milk Products Group
|1 ounce cheese
||Pair of dice or the size of your thumb
|1 ½ ounces cheddar cheese
||2 (9-volt) batteries
|1 cup of milk
||8 ounce carton of milk
|8 ounces yogurt
||Baseball or tennis ball
|Meat & Beans Group
|3 ounces of meat, fish or poultry
||Deck of cards (3 servings)
|2 tablespoons of peanut butter
||Ping–pong ball (2 servings)
|½ cup cooked beans
||Baseball (2 servings)
Try these ideas to help control portions at home:
- When your child is hungry and looking for a snack take the amount of food that is equal to one serving (refer to the Nutrition Facts label) and have your child eat it off a plate instead of eating it out of the box or bag.
- Don’t be tempted to finish off leftover dinner the next day. Freeze leftovers as single servings so that you can pull it out of the freezer when you need a quick, healthy meal for your family.
- Be prepared and have emergency snacks on hand if your family is running late and needs a quick snack. Make your own snack bags for traveling by reading the Nutrition Facts label and placing a single serving size into plastic bags.
- Have your child measure out a single serving of food before sitting in front of the television or doing other activities that can distract him/her from realizing how much food is being consumed. This way your child will know exactly how much he or she is eating!
Serving sizes on food labels are sometimes different from the Food Guide Pyramid servings. For example, the serving size for beverages is measured in cups or fluid ounces. Whether it is milk, juice, or soda the nutrition facts labeling guidelines is 1 cup or 8 fluid ounces, which equals 1 serving size. However, the Food Guide Pyramid serving size for milk is 1 cup, but for juice it is ¾ cup.
So, even though the amount of 1 serving on nutrition facts labels and the Food Guide Pyramid may be slightly different it is still a great tool to help you and your child decide if you are getting enough or too much food each day. Encourage your child to get familiar with the serving sizes because smart eating is an essential part of growing and staying healthy!
Source: Nourish Interactive.
By Michelle Mirizzi MS Registered Dietitian
Most of us already know that breakfast is the most important meal of the day. Beginning your day without breakfast is like trying to fly a kite without any wind. It's hard to get started and even harder to keep going. Breakfast is the first chance your child's developing body and brain has to refuel its glucose levels, (that's the brains basic fuel), after several hours of sleep.
Why is breakfast the most important meal of the day? Here are just a few reasons why your child should eat breakfast:
Studies show that eating breakfast everyday is important in maintaining a healthy body weight. Starting your child's day with a healthy breakfast will also make them less likely to eat high-calorie snacks during the morning. Eating a well balanced breakfast improves their intake of fiber, vitamins and minerals, especially iron and vitamin C; these nutrients are essential in a balanced diet. In fact, a good breakfast provides one-fourth to one-third of the day's energy and nutrient needs. Children who eat a healthy breakfast tend to show improved academic performance, longer attention span, better attendance and decreased hyperactivity in school. Skipping breakfast will often make your child feel tired, restless or irritable by mid-morning. By eating breakfast, your child will have energy throughout the morning and help him/her concentrate better in class. This also means fewer trips to the school nurse's office.
Breakfast can be served hot or cold, sitting down or eaten on-the-run. Breakfast can be a typical breakfast food, or left-overs from dinner the night before. The main point to remember is to include it in your morning routine for both you and your child. A good breakfast is easier than you think. By choosing the right foods, you can feed your child quickly at home or create a brown bag to go.
A nutritious breakfast includes foods from at least three of the five food groups:
Fruit group; fresh whole fruit such as bananas, apples, oranges. Sliced fruit which can be added to cereal, yogurt or oatmeal.Vegetables group; 100% vegetable juice, or mushrooms, asparagus, or green peppers in an omelet.Grains group; whole-grain breads, dry cereal, bagels, english muffins, flour tortillas, rice.Milk group; low fat or fat free milk, yogurt or cheese. If your child is lactose intolerant, choose lactose-free products that still have the calcium and other nutrients needed.Meat and beans group; eggs, lean meat, peanut butter, beans.
Traditional and non-traditional breakfast ideas:
Whole grain cereal with fruit and low fat milkOatmeal with raisins and low fat milkWaffles, turkey bacon and fruit juiceBagel with cheese or peanut butterBreakfast burrito: scrambled eggs, cheese and veggies wrapped in a flour tortillaGrilled cheese sandwich and juiceTurkey sandwich and a cup of low fat milkRice bowl with chicken and vegetables on top
Follow these easy tips to make time for breakfast in the morning:
Do some of your morning chores the night before, such as selecting clothes to wear and getting backpacks ready for school. Set the alarm for 15 minutes earlier to allow more time to prepare and eat breakfast as a family.Skip the audio-video temptation: make breakfast time about eating rather than watching TV, playing a video game or using the computer. You may find it easier to get out of the house on time as well.Offer something non-traditional like leftovers from the night before. Eating nutritious food for breakfast is better than eating no breakfast at all.Have items available in your kitchen that can be quickly and easily assembled in the morning such as whole grain cereals with milk, fresh fruit, yogurt or bagels.Pick one morning a week where you make a special breakfast such as pancakes and eggs. You can set up the mix the night before or even make the pancakes and freeze them to reheat when needed.
Creating healthy habits
Children are “copycats”; They like to do what someone else is doing. Parents and older siblings can act as role models by setting a good example and taking the time to eat breakfast every morning. Rise and shine with breakfast and help your child develop a healthy habit that will benefit them throughout their life.
This family wellness article is provided by Nourish Interactive, visitwww.nourishinteractive.com for nutrition articles, family wellness tips, free children's healthy games, and tools. Available in English and Spanish.
Copyright ©2009 Nourish Interactive – All Rights Reserved.
In the survey, commissioned by Act Against Allergy, further impact on family life was revealed. As a direct result of having a child with CMA, half (49%) the respondents have missed work, over a third (38%) have argued with their partner and 39% said the lives of other children in the family have also been disrupted.1
These findings were no surprise to Natalie Hammond, from Hertfordshire, UK, whose son Joe was diagnosed with CMA when he was six months old. Joe was initially misdiagnosed and even underwent surgery for a twisted bowel before doctors finally discovered that CMA was the cause of his illness. Mrs. Hammond said: “It was heartbreaking and frightening seeing Joe so sick – he would vomit and had blood in his stools. We felt utterly powerless, and couldn't believe a simple food like milk could do this. It took a long time to get over this terrifying and stressful experience.”
Cows' milk is one of the European Union's 'big eight' allergy-inducing foods alongside gluten, eggs, fish, peanuts, soya, treenuts and shellfish. More serious than lactose intolerance, a true milk allergy presents in one or more of three organ systems:
– Gastrointestinal (vomiting, diarrhoea, abdominal cramps, bloating) – affecting 50-60% of those with CMA
– Skin (rashes, including eczema and atopic dermatitis) – 50-70%
– Respiratory (wheeze, cough, runny nose) – 20-30%3
For further information on cows' milk allergy, see: www.actagainstallergy.com
Food allergies, by some accounts, affect about 4 percent of adults and 5 percent of children under the age of 6 in the United States, though this study raises questions about the reliability of such figures.
Food allergies can cause a variety of problems, ranging from mild skin rashes or nausea to a life-threatening, whole-body reaction known as anaphylaxis. The allergies can also have serious effects on patients' social interactions, school and work attendance, family economics and overall quality of life. “It's a life-defining diagnosis in a way,” said Chafen.
The National Institute of Allergy and Infectious Diseases is working on new clinical practice guidelines and, as part of its efforts, enlisted Chafen and her colleagues to review the current evidence on food allergies.
The researchers started their work by sifting through thousands of scientific papers, published between 1988 and 2009, that focused on the four foods — milk, eggs, fish and peanut and tree nuts — responsible for more than half of all allergies. They ultimately reviewed 72 studies, including one meta-analysis on prevalence, 18 studies on diagnosis, 28 studies on management, and four meta-analyses and 21 additional studies on prevention.
When examining the literature, the researchers found there was no universal definition of “food allergy,” in spite of NIAID's defining it as an “adverse immune response” that is “distinct from other adverse responses” such as a food intolerance. In fact, 82 percent of the studies provided their own definition of food allergy.
“This validates the idea that there exists a great deal of complexity and confusion in the field of food allergy, even at the level of the medical literature,” said co-author Marc Riedl, MD, MS, section head of clinical immunology and allergy at UCLA.
Along the same lines, there was a lack of uniformity for criteria in making a diagnosis. The current gold standard is the food challenge, during which a physician gives a patient a sample of the suspected offending food, sometimes in capsule form, and then monitors for allergic reaction. However, this test requires specialized personnel, is expensive and has a risk of anaphylaxis. Office-based tests were used to diagnose many patients; these include a skin-prick test, during which a dilute extract of the potential allergen is placed on the skin, and a blood test that determines the presence of food-specific allergic antibodies known as IgE.
As the researchers discuss in their paper, the concern with the latter two tests is that they're not definitive: Patients with non-specific symptoms, such as a rash or digestive troubles, and positive skin-prick or blood tests actually have less than a 50 percent chance of having a food allergy. In order to make a proper diagnosis, they pointed out, physicians need to evaluate the data within the context of a patient's history and have a great understanding of symptoms consistent with true food allergy.
What this means, then, is there is a potential for the overdiagnosis of food allergy.
“I frequently see patients in my clinical practice who have food intolerance, but have previously had inadequate or inappropriate evaluation and been told they have a 'food allergy',” said Riedl. “This causes a great deal of unnecessary anxiety and concern for the patient.”
Previous studies have tried to determine whether the skin-prick or blood test is superior over the other, but in reviewing the evidence, Chafen and her colleagues found “no statistical superiority in either test.” They also found generally inconclusive results from 10 previous studies in which the tests were combined, in an effort to improve diagnostic accuracy.
“I was very surprised,” said Chafen. “I'm a general internist and I thought diagnostic strategies were more-studied.”
In terms of treatment, Chafen said expert opinion is that an elimination diet — having the patient stop consuming the food that causes the allergic reaction — is the most common. Although the approach is a common-sense one (“If a patient breaks out in hives repeatedly after drinking milk, it's your instinct as a physician to say, 'Don't drink milk,'” Chafen said), the researchers found the treatment hasn't been well-studied.
It would be unethical to conduct controlled studies of elimination diets for patients with serious, life-threatening allergic reactions, but as pointed out in the paper, there are few studies of this approach on patients with relatively minor symptoms.
“In these instances, the benefits of an elimination diet are uncertain based on published evidence and potential benefits need to be weighed against the potential nutritional risks of such a diet, particularly in children,” the researchers wrote.
Chafen and her colleagues also found that immunotherapy, a treatment in which the body's immune system is altered by administering increasing doses of the allergen over time, appeared to be effective at eliminating symptoms in the short term. Immunotherapy isn't a licensed method for allergy treatment, but the researchers urged more study on its long-term effect and safety.
In all, the researchers concluded, the food-allergy field is in need of uniformity in the criteria for what constitutes an allergy and a set of evidence-based guidelines upon which to make this diagnosis. NIAID, which put together an expert panel and has reviewed the group's analysis, is planning to finalize such guidelines later this summer.
As for Chafen, who sees patients with potential food allergies, these findings have encouraged her to rely more on specialists to help clinch a diagnosis. “People need to be seen by someone with a deep understanding of diagnostic tests and criteria,” she said. “The distinction between food intolerance and food allergy is really important.”
The study was funded by NIAID. Other Stanford authors on the study are Dena Bravata, MD, a PCOR affiliate; and Vandana Sundaram, MPH, assistant director of research for CHP/PCOR. Paul Shekelle, MD, PhD, with the RAND Corp.'s Southern California Evidence-Based Practice Center and the West Los Angeles VA Medical Center, is the senior author.
People with lactose intolerance do not produce enough of the enzyme lactase to break down lactose (the form of sugar naturally found in milk). Instead, when people with lactose intolerance ingest large amounts of dairy products, or foods or medicines containing lactose, lactose stays in the intestinal tract until it reaches the colon where it can cause gas, bloating, stomach cramps or diarrhea.
Last February, the National Institutes of Health (NIH) released a statement on lactose intolerance and health to provide health care providers, patients and the general public with the latest information on the topic.
“What many people fail to understand is that lactose intolerance is not an all-or-nothing situation,” says Susan Nitzke, professor of Nutritional Sciences at the University of Wisconsin-Madison and nutrition specialist with the University of Wisconsin-Extension.
Nitzke points out that many people with lactose intolerance can consume small amounts of lactose–for example, a half cup of milk or yogurt–without experiencing any symptoms. “This is especially true if the milk or other lactose-containing food is consumed with a meal,” she says.
Nitzke urges people to consult their doctor or a dietitian (like Nastaran) before making drastic dietary changes for suspected lactose intolerance. Your doctor may do a blood, breath or stool test to find out if lactose intolerance is the true cause of your digestive problems.
Milk and dairy foods provide many important nutrients. Milk is a well-known source of calcium and vitamin D. “Dairy products are also excellent sources of protein, potassium and many other vitamins and minerals,” says Mallory Koenings, a graduate student in the Department of Nutritional Sciences at UW-Madison.
Because dairy products contain so many important nutrients, even people who are lactose-intolerant are urged to consider alternatives within the milk food group, such as yogurt or lactose-free milk.